Wholesale prices for big-selling Jif are going up 30 percent starting in November, while Peter Pan will raise prices as much as 24 percent in a couple of weeks. Unilever would not comment on its pricing plans, but a spokesman for Wegmans Food Markets said wholesale prices for all brands it carries, including Skippy, are 30 percent to 35 percent higher than a year ago.

The US Department of Agriculture estimates the current spot price for a ton of unprocessed Runner peanuts, commonly used in peanut butter, at about $1,150 a ton, which is up from about $450 a year ago. A pound of shelled peanuts, meanwhile, would fetch $1.20 currently, one broker said, up from 52 cents a year ago.

The tight peanut supply means peanut butter costs will eventually make their way to consumers, who are facing higher prices on just about everything they buy in the supermarkets.

As with any crop, the challenges facing peanut farmers begin and end with the weather. In Georgia, the leading US peanut producing state, the planting season was the driest in memory for John Harrell, 56, a sixth-generation peanut farmer.

"I don't remember a year that you didn't catch a shower or had so little moisture in the ground to get the seed up," said Harrell.

Compounding the problems was that some farmers devoted more of their fields to crops like cotton, which was fetching a high price. The United States Department of Agriculture estimates a 17 percent drop in the peanut crop this year, to 3.46 billion pounds.

Of added concern is the quality of the crop. Scorching heat, especially in Texas, singed many peanut plants as they developed, leaving more peanuts destined to be processed into oil, rather than the edible quality that is shelled and turned into peanut butter. Only 38 percent of the US peanut crop was rated good or excellent last month, down from about 60 percent a year ago.